include/Producer.hpp

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+#pragma once
+// Producer.hpp
+// SPDX-License-Identifier: GPL-3.0-or-later
+// Author: Unai Blazquez <unaibg2000@gmail.com>
+#include <atomic>
+#include <chrono>
+#include <functional>
+#include <thread>
+
+#include "SysfsRead.hpp"
+
+using RandomFn = std::function<int()>;
+using SleepFn = std::function<void(std::chrono::milliseconds)>;
+class Producer
+{
+ public:
+  /// @brief Construct a Producer bound to a sysfs-like control file.
+  /// @param sysfs_path Path to the control file (e.g. "./fake_sysfs_input").
+  /// @param send_fn    Function called whenever a new integer should be sent.
+  /// @param sleep_fn   Stub for sleeping function, allows reducing sleep on
+  /// testing
+  Producer(const std::filesystem::path& sysfs_path,
+           std::function<void(int)> send_fn, RandomFn random_fn,
+           SleepFn sleep_fn = default_sleep);
+
+  /// @brief Start the worker thread. Safe to call only once.
+  void start();
+
+  /// @brief Request the worker thread to stop and wait for it to finish.
+  void stop();
+
+ private:
+  /// @brief Main loop executed by the worker thread.
+  void run_loop();
+
+  std::thread m_thread;
+  std::atomic<bool> m_running;
+  SysfsReader m_reader;
+  RandomFn m_random;
+  SleepFn m_sleep;
+  static void default_sleep(std::chrono::milliseconds d)
+  {
+    std::this_thread::sleep_for(d);
+  }
+  std::function<void(int)> m_send;
+};

src/core/Producer.cxx

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+// Producer.cxx
+// SPDX-License-Identifier: GPL-3.0-only
+// Author: Unai Blazquez <unaibg2000@gmail.com>
+
+#include "Producer.hpp"
+
+#include "SysfsRead.hpp"
+
+Producer::Producer(const std::filesystem::path& sysfs_path,
+                   std::function<void(int)> send_fn, RandomFn random_fn
+    : m_reader(sysfs_path),
+      m_send(std::move(send_fn)),
+      m_random(std::move(random_fn)),
+      m_sleep(std::move(sleep_fn))
+{
+}
+void Producer::start()
+{
+  m_running.store(true);
+  m_thread = std::thread(&Producer::run_loop, this);
+}
+
+void Producer::stop()
+{
+  m_running.store(false);
+  if (m_thread.joinable())
+  {
+    m_thread.join();
+  }
+}
+void Producer::run_loop()
+{
+  auto status = m_reader.read_status();
+  switch (status)
+  {
+    case SysfsStatus::Enabled:
+      m_send(m_random());
+      break;
+
+    case SysfsStatus::Unreachable:
+      // do nothing for now
+      break;
+
+    case SysfsStatus::Empty:
+      break;
+
+    case SysfsStatus::ErrorTempTooHigh:
+      break;
+
+    case SysfsStatus::UnexpectedValue:
+      break;
+  }
+  m_sleep(delay);
+  // Thread will end here (for now) stop will join it
+}

tests/test_producer.cxx

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+#include <gtest/gtest.h>
+
+#include <chrono>
+#include <fstream>
+
+#include "Producer.hpp"
+
+TEST(ProducerTest, ProducerCallsBackWhenEnabled)
+{
+  // Arrange create the file and write "1\n" into it.
+  {
+    std::ofstream out("fake_sysfs_input");
+    out << "1\n";
+  }
+  // create a fake callback function
+  std::vector<int> outputs;
+
+  // construct a producer with fake file and callback
+  Producer producer{"fake_sysfs_input", [&outputs](int value)
+                    { outputs.push_back(value); }, []() { return 42; }};
+  // Act: initialize producer and stop it.
+  producer.start();
+  std::this_thread::sleep_for(std::chrono::milliseconds(1));  // ← 1ms window
+  producer.stop();
+
+  // Assert: we expect one output being 42
+  ASSERT_EQ(outputs.size(), 1u);
+  EXPECT_EQ(outputs[0], 42);
+}
+
+TEST(ProducerTest, ProducerDoesNotCallWhenUnexpectedValue)
+{
+  // Arrange create the file and write "0\n" into it.
+  {
+    std::ofstream out("fake_sysfs_input");
+    out << "0\n";
+  }
+
+  std::vector<int> outputs;
+
+  Producer producer{"fake_sysfs_input",
+                    [&outputs](int value) { outputs.push_back(value); },
+                    []() { return 42; }, [](std::chrono::milliseconds) {}};
+
+  producer.start();
+  std::this_thread::sleep_for(std::chrono::milliseconds(1));  // ← 1ms window
+  producer.stop();
+
+  // Assert: we expect no output
+  EXPECT_TRUE(outputs.empty());
+}
+
+TEST(ProducerTest, ProducerDoesNotCallWhenEmpty)
+{
+  // Arrange create the file and write "0\n" into it.
+  {
+    std::ofstream out("fake_sysfs_input");
+    out << " ";
+  }
+
+  std::vector<int> outputs;
+
+  Producer producer{"fake_sysfs_input",
+                    [&outputs](int value) { outputs.push_back(value); },
+                    []() { return 42; }, [](std::chrono::milliseconds) {}};
+
+  producer.start();
+  producer.stop();
+
+  // Assert: we expect no output
+  EXPECT_TRUE(outputs.empty());
+}
+
+TEST(ProducerTest, ProducerDoesNotCallWhenUnreachable)
+{
+  std::vector<int> outputs;
+  std::vector<std::string> logs;
+
+  Producer producer{"nonexistant_sysfs_input",
+                    [&outputs](int value) { outputs.push_back(value); },
+                    []() { return 42; }, [](std::chrono::milliseconds) {}};
+
+  producer.start();
+  std::this_thread::sleep_for(std::chrono::milliseconds(1));  // ← 1ms window
+  producer.stop();
+
+  // Assert: we expect no output
+  EXPECT_TRUE(outputs.empty());
+}
+
+TEST(ProducerTest, ProducerDoesNotCallWhenTempTooHigh)
+{
+  // create  a file that contains error
+  {
+    std::ofstream out("fake_sysfs_input");
+    out << "error: temp too high";
+  }
+  std::vector<int> outputs;
+
+  Producer producer{"fake_sysfs_input",
+                    [&outputs](int value) { outputs.push_back(value); },
+                    []() { return 42; }, [](std::chrono::milliseconds) {}};
+
+  producer.start();
+  std::this_thread::sleep_for(std::chrono::milliseconds(1));  // ← 1ms window
+  producer.stop();
+
+  // Assert: we expect no output
+  EXPECT_TRUE(outputs.empty());
+}